Thermotropic liquid crystalline polymers (LCPs) are commercially important being particularly useful as molding resins where certain attributes, such as short molding cycles, low flammability, good moldability, stability at high temperatures, and/or chemical resistance are required. LCPs are used, inter alia, to make automotive parts, electrical and electronic parts such as connectors, and other small or difficult to mold parts.
One drawback to the use of such polymers has been the relatively high price of LCPs, which is partly due to the fairly expensive monomers used in their manufacture. Therefore it it has long been desired to not only find LCPs with improved properties, but also to find such LCPs that could be made from more reasonably priced and readily available monomers.
U.S. Pat. No. 4,169,933 describes the preparation of polymers containing repeat units derived from hydroquinone, terephthalic acid, 2,6-naphthalene dicarboxylic acid and 4-hydroxybenzoic acid. U.S. Pat. Nos. 5,079,289; 5,097,001; and 5,221,730 describe the preparation of polymers containing repeat units derived from hydroquinone, terephthalic acid, isophthalic acid and 4-hydroxybenzoic acid. Polymers of this invention are not described in any of these patents.
U.S. Pat. No. 5,492,946 relates to LCPs, and U.S. Pat. No. 4,851,497 to aromatic polyesters